Periodic Reporting for period 1 - iPLUG (Distributed multiport converters for integration of renewables, storage systems and loads while enhancing performance and resiliency of modern distributed networks)
Reporting period: 2022-09-01 to 2024-02-29
IPLUG general objective is to design a new breed of multiport converters and develop the methodologies to locate, size, operate and control multiple converters in distribution networks with high penetration of renewables and various AC and DC loads.
* Objective 1: Requirements, architecture and assessment of multi-port converters including high penetration of renewables, energy storage and different AC and DC loads.
* Objective 2: Design the hardware and control of multiport converters for medium-voltage applications.
* Objective 3: Design the hardware and control of multiport converters for low-voltage applications.
* Objective 4: Optimization based methodology for location and sizing of distributed multiport converters.
* Objective 5: Application of advanced operation and control techniques for local and coordinated control of multiport converters in a distribution network for optimised, stable and secure operation.
* Objective 6: Helping rapid penetration and acceptance of renewable energy and electrical systems by enhancing the environmental, social and economic aspects.
* Objective 1: Requirements, architecture and assessment of multi-port converters including high penetration of renewables, energy storage and different AC and DC loads.
* Objective 2: Design the hardware and control of multiport converters for medium-voltage applications.
* Objective 3: Design the hardware and control of multiport converters for low-voltage applications.
* Objective 4: Optimization based methodology for location and sizing of distributed multiport converters.
* Objective 5: Application of advanced operation and control techniques for local and coordinated control of multiport converters in a distribution network for optimised, stable and secure operation.
* Objective 6: Helping rapid penetration and acceptance of renewable energy and electrical systems by enhancing the environmental, social and economic aspects.
Objective 1
● Wide scope review of grid codes and standards relevant to multiport power converters (MPCs) and the devices that they are expected to interface (on low and medium voltages)
● Identification of areas (and translation to quantitative KPI metrics) that MPCs can provide value for distribution network applications
● Wide review of existing MPC topologies, with consideration of strengths and weaknesses relating to the above-mentioned KPI metrics
● Initiation of design considerations discussion amongst MPCs amongst partners, exploring differences for low and medium voltage applications
● Utilisation of information from reviews of grid codes and standards, MPC topologies, and from design consideration discussion to inform key requirements for MPC ports
● Definition of case studies and collation of relevant data relating to areas that MPCs are deemed to be able to provide value
● Review of control and communication technologies used for MPC or similar applications
Objective 2
● Simulation model of various detail (average and switching models) for two multiport converter categories (isolated and non-isolated) are developed to integrate two ac-ports and one dc-port.
● Different modulation and control strategies for the converters are developed and their performance is verified in simulation both in normal and abnormal operation conditions.
● Control and modelling of dual-, triple- and multi-active bridge DC-DC converters for isolation stage is performed.
● Implementation of grid-forming capability in multiport converters in a challenging low X/R grid scenario.
● Currently working on comparison of multiport topologies based on KPIs defined from WP1.
Objective 3
● Control strategies are developed to provide FRT capability for MPCs.
● Stability analysis approach is proposed as a tool to for analyzing stability and devising stabilization methods for DC-DC converters.
● A multiport Y-converter (YMPC) is proposed to link the three-phase AC grid with DC systems.
● A comprehensive evaluation of the proposed YMPC against state-of-the-art converters is conducted.
● An asymmetric multiport Y-converter (AYMPC) is proposed to link the three-phase AC grid with DC systems
● The performance of the proposed converters and control techniques is validated using experimental prototypes and HIL simulations.
Objetive 4
● Optimization methodology developed to size and locate multiport converters in distribution grids.
● GIS-based approach to evaluate the resilience of a network and determine the most critical regions where mitigation actions are preferred.
● Currently working on applications to relevant use cases.
Objective 5
● Anell LV grid (Use Case 4) modelled for real-case grid studies.
● Initial power flow analyses on Anell LV grid carried out.
● Switching, average and small-signal model of a Soft Open Point (SOP) based on a Triple active bridge (TAB) developed.
● Grid-following control of the TAB-based SOP developed.
● Stability analysis of the grid-connected, TAB-based SOP carried out.
● Grid-forming control for enhanced Soft Open Point using a non-isolated DC-coupled topology developed.
● Sliding Mode Control of TAB developed.
● Control capability (inversion/rectification limits, islanding capability) and fault-current limitation by grid-forming and grid-following controllers on very low (simplified) X/R distribution networks initially explored.
● Wide scope review of grid codes and standards relevant to multiport power converters (MPCs) and the devices that they are expected to interface (on low and medium voltages)
● Identification of areas (and translation to quantitative KPI metrics) that MPCs can provide value for distribution network applications
● Wide review of existing MPC topologies, with consideration of strengths and weaknesses relating to the above-mentioned KPI metrics
● Initiation of design considerations discussion amongst MPCs amongst partners, exploring differences for low and medium voltage applications
● Utilisation of information from reviews of grid codes and standards, MPC topologies, and from design consideration discussion to inform key requirements for MPC ports
● Definition of case studies and collation of relevant data relating to areas that MPCs are deemed to be able to provide value
● Review of control and communication technologies used for MPC or similar applications
Objective 2
● Simulation model of various detail (average and switching models) for two multiport converter categories (isolated and non-isolated) are developed to integrate two ac-ports and one dc-port.
● Different modulation and control strategies for the converters are developed and their performance is verified in simulation both in normal and abnormal operation conditions.
● Control and modelling of dual-, triple- and multi-active bridge DC-DC converters for isolation stage is performed.
● Implementation of grid-forming capability in multiport converters in a challenging low X/R grid scenario.
● Currently working on comparison of multiport topologies based on KPIs defined from WP1.
Objective 3
● Control strategies are developed to provide FRT capability for MPCs.
● Stability analysis approach is proposed as a tool to for analyzing stability and devising stabilization methods for DC-DC converters.
● A multiport Y-converter (YMPC) is proposed to link the three-phase AC grid with DC systems.
● A comprehensive evaluation of the proposed YMPC against state-of-the-art converters is conducted.
● An asymmetric multiport Y-converter (AYMPC) is proposed to link the three-phase AC grid with DC systems
● The performance of the proposed converters and control techniques is validated using experimental prototypes and HIL simulations.
Objetive 4
● Optimization methodology developed to size and locate multiport converters in distribution grids.
● GIS-based approach to evaluate the resilience of a network and determine the most critical regions where mitigation actions are preferred.
● Currently working on applications to relevant use cases.
Objective 5
● Anell LV grid (Use Case 4) modelled for real-case grid studies.
● Initial power flow analyses on Anell LV grid carried out.
● Switching, average and small-signal model of a Soft Open Point (SOP) based on a Triple active bridge (TAB) developed.
● Grid-following control of the TAB-based SOP developed.
● Stability analysis of the grid-connected, TAB-based SOP carried out.
● Grid-forming control for enhanced Soft Open Point using a non-isolated DC-coupled topology developed.
● Sliding Mode Control of TAB developed.
● Control capability (inversion/rectification limits, islanding capability) and fault-current limitation by grid-forming and grid-following controllers on very low (simplified) X/R distribution networks initially explored.
WP1
● Identification of GC and standard procedures that require development to enable the safe integration of multiport devices into networks
● Application of DC installation safety zones to MPCs to define the requirement of isolation for given port specifications
● Development of high-level Pugh Matrix comparison tool to compare MPC topologies for specific applications
● Identification of suitability of isolated and partially isolated MPC topologies for the applications
● Identification of niche for development of more operationally capable non-isolated DC capable MPC
WP2
● Development of modulation and control of fully isolated MPC converter that has good dynamic performance during normal and faulty conditions.
● Control of multi-active bridge DC-DC converter with control of both power exchange between primary and secondary sides as well as dc-voltage control on one of the secondary side ports that will make up the dc-port of the MPC. A control and configuration that can withstand a loss of an active bridge is demonstrated.
● Development of mixed level- and phase-shifted modulation strategy for the multilevel converter that improves switching losses but improves harmonic content. The modulation scheme enables no need of sorting to balance the submodule voltages.
● Development of uni-polar based modulation strategy for the multi-active bridge DC-DC converters that improves the harmonic content. The method still inherits the simplicity and robustness of the conventional phase-shifted modulation of active-bridge converters.
WP3
* Introduced innovative approaches for providing Fault-Ride Through capability to multiport power converters (MPCs).
* Proposed the utilization of multiple-input multiple-output (MIMO) admittance passivity properties, offering a novel method to analyze stability and develop stabilization techniques for DC-DC converters.
* Devised novel MPC topologies aimed at improving the interface between three-phase AC grids and DC systems, resulting in more compact, flexible, and highly efficient power converters compared to existing topologies.
* Comprehensively evaluated the performance of these proposed topologies through analysis, simulations, and experimental prototypes.
WP4
* Small-signal model and stability analysis of a three port soft open point: The stability analysis of the TAB-based soft open point is not available in the scientific literature and represents a research novelty.
● Identification of GC and standard procedures that require development to enable the safe integration of multiport devices into networks
● Application of DC installation safety zones to MPCs to define the requirement of isolation for given port specifications
● Development of high-level Pugh Matrix comparison tool to compare MPC topologies for specific applications
● Identification of suitability of isolated and partially isolated MPC topologies for the applications
● Identification of niche for development of more operationally capable non-isolated DC capable MPC
WP2
● Development of modulation and control of fully isolated MPC converter that has good dynamic performance during normal and faulty conditions.
● Control of multi-active bridge DC-DC converter with control of both power exchange between primary and secondary sides as well as dc-voltage control on one of the secondary side ports that will make up the dc-port of the MPC. A control and configuration that can withstand a loss of an active bridge is demonstrated.
● Development of mixed level- and phase-shifted modulation strategy for the multilevel converter that improves switching losses but improves harmonic content. The modulation scheme enables no need of sorting to balance the submodule voltages.
● Development of uni-polar based modulation strategy for the multi-active bridge DC-DC converters that improves the harmonic content. The method still inherits the simplicity and robustness of the conventional phase-shifted modulation of active-bridge converters.
WP3
* Introduced innovative approaches for providing Fault-Ride Through capability to multiport power converters (MPCs).
* Proposed the utilization of multiple-input multiple-output (MIMO) admittance passivity properties, offering a novel method to analyze stability and develop stabilization techniques for DC-DC converters.
* Devised novel MPC topologies aimed at improving the interface between three-phase AC grids and DC systems, resulting in more compact, flexible, and highly efficient power converters compared to existing topologies.
* Comprehensively evaluated the performance of these proposed topologies through analysis, simulations, and experimental prototypes.
WP4
* Small-signal model and stability analysis of a three port soft open point: The stability analysis of the TAB-based soft open point is not available in the scientific literature and represents a research novelty.